When Tom Bradby arrived in Belfast as ITN's newly appointed Ireland correspondent in 1993, the Troubles were raging, Bishopsgate had just been bombed and the peace process was no more than a whispered rumour. The new film Shadow Dancer – adapted by Bradby from his late 1990s novel of the same name – shows how far we have come since then.

"It really hit home for me when I saw the Queen shaking hands with Martin McGuinness the other month," says Bradby, now ITN's political editor. "I was gobsmacked by that and very uplifted by it too. It shows that anything is possible in the world."

Shadow Dancer, to be released on Friday 24 August, opens in the early 1970s before switching to the 1990s when the British security forces had infiltrated every level of the Provisional IRA. Andrea Riseborough plays a Republican single mother who is coerced into spying on her extended family by an MI5 agent, played by Clive Owen. Both protagonists are eventually revealed to be pawns in a wider game – and forced to rely on each other in order to survive.

The film is based on Bradby's own experiences in Belfast, where he lived from 1993 to 1996. His tenure covered the IRA ceasefire, Bill Clinton's Belfast rally and the fraught runup to the Good Friday agreement.

"It was my good luck to be there at a crucial time," he said. "I only got the job because the older, more experienced reporters didn't go for it. They were sick of the place and assumed that nothing would ever change.

"But three weeks into the job I heard the first whispers that the IRA were thinking about taking a different path. Some colleagues were very cynical – they thought it was a trick. But I knew nothing about anything. I came without any baggage, which was probably for the best."

Shadow Dancer was directed by James Marsh, the British film-maker who won an Oscar for his 2008 documentary Man on Wire. Marsh admits that he initially hesitated over the project, reluctant to excavate such painful recent history. "It was about Ireland and the Troubles, and we are all glad to have got beyond that," he said.

Yet Bradby, now 45, feels that the film's themes speak to today's headlines as much as to the archive.

"Yes, the film is set in Northern Ireland, but it could have been anywhere. It's about people caught up at the heart of a vicious conflict and the choices they make in a life or death situation. A similar situation might just as easily be taking place in Cairo or Aleppo."

On leaving Northern Ireland, Bradby progressed through stints as ITN's Asia correspondent and royal correspondent. He currently juggles his day job as political editor with his sideline as a novelist and is in the process of adapting another of his books – the Shanghai-based historical thriller The Master of Rain – for the screen.

Meanwhile, his recent visits to Belfast have reminded him how far the city has travelled in the past two decades. "I think I've always been more interested in humanity than politics," he said. "The best stories are the ones about the ordinary human beings who are caught in the vortex, mired in the misery. What's most inspiring about Northern Ireland is the way in which the people caught in that vortex were able to march themselves out of it."

In so doing, perhaps, they set an example for the politicians. "I'll tell you what was even more remarkable than McGuinness shaking hands with the Queen," said Bradby. "It was watching McGuinness and Ian Paisley sitting together at Stormont as though they'd been mates forever, laughing away like the Chuckle Brothers.

"We could never have conceived of that 20 years ago – the idea that two men with that much history would ever arrive at that kind of relationship.

"Although maybe it was that recognition of shared history that allowed them to get there. Maybe they got to the point where they stopped making judgments. They recognised that they had both been in the same boat all along."